1. Field of the Invention
Embodiments of the present invention relate, in general, to medical imaging systems and, notably, to X-ray apparatuses used in the field of medical imaging. More specifically, the subject matter of the invention relates generally to X-ray imaging apparatuses that are mounted on a mobile device.
2. Description of the Related Art
X-ray apparatuses conventionally comprise an imaging assembly including an X-ray tube and an X-ray detector placed opposite the X-ray tube in a direction of emission of the X-rays. The tube and the detector are usually placed on two mutually opposite ends of an arm, so that the X-rays emitted by the tube can be incidental to and detected by the detector.
Such apparatuses are used for angiographic examinations with a diagnostic or an interventional aim.
During these examinations, it is necessary to produce radiographs of a region of interest in the body of a patient irradiated by X-rays. For this purpose, after the patient has been laid out on an examination table, the X-ray tube and the detector are brought to face the region to be radiographed and to be centred around the region of interest.
In the prior art, several types of X-ray apparatuses are known to produce radiographs.
First, X-ray apparatuses are known that are fixed to the ground, and in which the arm supporting the X-ray tube and the detector comprises several degrees of freedom, making it possible to position the X-ray beam facing the region of interest.
This type of apparatus however has a major drawback, relating to the fact that the radiography requirement is necessary only at the beginning and at the end of the intervention.
Meanwhile, the patient access should take precedence. However, the apparatus cannot be removed from the examination table when it is not used, such that, in particular, the transfer and installation of the patient on the examination table are altered by the presence of this cumbersome system.
Besides, conventional mobile X-ray imaging systems may be mounted on a carriage that can be moved manually and that contains a certain number of batteries used to supply the X-ray tube with power.
This type of apparatus is not suitable for angiographic examination because the necessary power delivered by the X-ray tube is no longer sufficient to obtain adequate image quality and, in particular, contrast.
Moreover, this type of mobile X-ray apparatus does not allow complex angulations because the diameter of the arm supporting the tube and the detector is not large enough.
Similarly, these mobile X-ray apparatuses do not achieve sufficient rotation speeds to allow good quality, three-dimensional image reconstructions. Finally, even though the weight of such an apparatus is half as much as that of an X-ray apparatus designed for angiography, it remains very difficult to move because of its relatively large dimensions and its weight, which can be up to 300 kg.
Moreover, X-ray apparatuses for angiography are known that are suspended to the ceiling and can be moved on guide rails, via a mobile carriage, for example with the aid of an electric motor.
This type of apparatus also has several drawbacks.
Firstly, many systems are already attached to the ceiling around the examination table, thus already cluttering the space around the patient, and making it difficult to install guide rails.
Secondly, mounting an X-ray apparatus on the ceiling considerably increases the risk of opportunistic contamination of the patient. Specifically, because of the difficulty of cleaning the rails, particles are likely to fall and contaminate the patient when the apparatus is sliding in the rails.
Moreover, in certain operating rooms, a sterile laminar flow is generated above the patient. In this case, the flow is likely to blow particles present on the rails, which can then enter the laminar flow and reach the patient.
There is therefore a need for a mobile imaging system that can be readily and automatically located in an operatic room and, notably, relative to an examination table.
Reference can be made to document FR 2 945 724 that discloses an X-ray imaging apparatus mounted on an automatic mobile device, which is capable of being moved automatically, either in a stand-alone manner, or under the control of a control console that can be operated by an operator. The X-ray apparatus is provided with a navigation system that can compute a trajectory for the imaging apparatus relative to a predefined trajectory.
However, it is necessary to determine the current position of the X-ray imaging apparatus to compute the trajectory and correct the computed trajectory relative to the predefined trajectory.
The current position can be determined either using optical readers operable to read or decode barcodes representative of a two-dimensional coordinates of their position in the environment, and to decode the information contained in the barcodes.
In another embodiment, the navigation system can be in communication with a GPS or global positioning system, operable to compute the position of the X-ray apparatus.
In a further example, the navigation system is operable to track the position of reflectors or detectors located in the operating room using a laser beam emitter and to compute the current position of the X-ray imaging apparatus from the duration between the incident laser beam and the reflected laser beam.
It has been found that such a navigation system is quite expensive and can be sensitive to disruptions from the environment interaction. In particular, the laser might be subject to booms, wall reflections or may be disrupted by outside light.
In the light of the foregoing, the object on the invention is to alleviate these drawbacks and to determine the position of an X-ray imaging apparatus without any interactions with the environment.